Thursday, 9 March 2017

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Detailed Lens Chart CCTV


Detailed Lens Chart CCTV Cameras
Naturally, lenses are on every security camera and have a dramatic affect on the area that the camera can monitor. Installing a security camera with the wrong type of lens can make that camera's video feed of little use.
A good rule of thumb to keep in mind when shopping for cameras is the smaller the lens' focal length, the mm spec, the wider your field of view will be.
For example, a camera with a 50mm lens will have a very narrow field of view (FOV) and be able to focus on objects far away while a 3mm lens will have a wide FOV and be more suited for short range monitoring.




Varifocal vs. Fixed Lenses

fixed lens is a lens that has a set focal length which you'll see as a 'x'mm spec. These lenses are only capable of viewing people / objects / areas a set distance away from the camera which will affect where you can install the camera.
varifocal lens is a lens that has an adjustable focal length which you will see as an 'x-y'mm spec. This allows the lens to be adjusted to view people / objects / areas at a distance of your choosing, grants you more flexibility with camera placement, and gives you more control on the focus clarity of that specific camera.
Each type of lens will aid in the capture of video regardless, but the varifocal lenses allow much more flexibility in the installation of a security camera system and allows you must more control over the quality of your video feeds.

CCTV Camera Lenses

There are many security cameras available and it would be impossible to cover them all in this guide. Security cameras produce images using CMOS (Complementary Metal Oxide Semiconductor) or CCD (Charge Couple Device) sensor chips. The size of the chip is normally 1/4", 1/3" or 1/2". As a rule of thumb, the larger the chip size, the higher the quality of the image produced and the higher the price. As technology has advanced, higher density 1/4" and 1/3" CCD chips can now produce as clear of an image as the older 1/3" & 1/2" chips.
Most cameras have the industry standard 3.6mm lens that provides roughly a 72 degree field of view. Figure 1.2 shows some popular lenses and their respective field of view:
Figure 1.2
Some cameras come with a varifocal lens so the focal length can be adjusted. Please visit our Lens Comparison Tool to learn more about lenses and field of view.



Field of View

The field of view (FOV) is the height and width of the picture size produced by a lens. FOV can be adjusted by using a different lens on your camera. There are two basic types of camera lenses: fixed focal (or monofocal) and varifocal (or zoom). FOV of a fixed focal lens cannot be adjusted. FOV of a varifocal lens can be adjusted. Varifocal lenses are usually more expensive. Figure 1.3 illustrates the FOV of various lenses.

Detailed Lens Chart
5 feet10 feet25 feet50 feet75 feet100 feet
2.8mm6.4 X 8.612.9 X 17.132.1 X 42.964.3 X 85.796.4 X 128.6128.6 X 171.4
4.0mm4.5 X 6.09.0 X 12.022.5 X 30.045.0 X 60.067.5 X 90.090.0 X 120.0
6.0mm3.0 X 4.06.0 X 8.015.0 X 20.030.0 X 40.045.0 X 60.060.0 X 80.0
8.0mm2.3 X 3.04.5 X 6.011.3 X 15.022.5 X 30.033.8 X 45.045.0 X 60.0
12.0mm1.5 X 2.03.0 X 4.07.5 X 10.015.0 X 20.022.5 X 30.030.0 X 40.0
16.0mm1.1 X 1.52.3 X 3.05.6 X 7.511.3 X 15.016.9 X 22.522.5 X 30.0
25.0mm0.7 X 1.01.4 X 1.93.6 X 4.87.2 X 9.610.8 X 14.414.4 X 19.2
50.0mm0.4 X 0.50.7 X 1.01.8 X 2.43.6 X 4.85.4 X 7.27.2 X 9.6
75.0mm0.2 X 0.30.5 X 0.61.2 X 1.62.4 X 3.23.6 X 4.84.8 X 6.4

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Glisten Security is a nationally recognized leader for video/audio surveillance, security alarm and access control solutions. We are committed to you and recognize that customer service is the key to success.

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